1. Field of the Invention
The present invention relates to broadheads and particularly to those with actuating blades.
2. Background
Bow hunters use either a fixed blade broadhead or a mechanical blade broadhead. A fixed blade broadhead, as shown in FIG. 1, has the blades 40, 40′ in a fixed position extending out from the arrowhead body 34. These extended blades may cause planing in flight, whereby the arrow does not drop over a flight path in a consistent manner and thereby makes it more difficult to reliably hit a target. In addition, fixed blades extend a substantial distance from the broadhead body and can create a lot of drag in flight which may reduce penetration into a game animal because of reduced velocity. The cutting surfaces 54 of the blades, as shown in FIG. 1, are exposed and may dull during penetration through an animal's hide. Many game animals have very tough hides which can quickly dull cutting surfaces. If arrowhead blades have a reduced sharpness after penetration through a hide, they may have a reduced penetration into the animal, and therefore not be as effective.
A mechanical blade insert 42 is shown in FIG. 2A having three mechanical blades 43 attached to an insert disc 44. The free ends of the blades are configured to extend forward from the insert disc when coupled to a broadhead 33. The mechanical blades are configured partially into a slot 35 within the arrow body 34. The free ends 76 of the mechanical blades 43 point forward, or in the direction of flight of the arrow when shot. The free ends are configured more proximal to the entry end of the broadhead when in a retained configuration as shown FIGS. 2B and 2C. The broadhead 33 is shown coupled to an arrow shaft 20 in FIG. 2C. A retainer 65 is typically configured around the mechanical blades to keep them in a forward position until the arrow 12 impacts a target, as shown in FIG. 2C. When the arrow 12 hits a target, the free ends 76 of the mechanical blades are forced backward and the retainer is released. The blades fall back into a deployed position as shown in FIG. 2D. The blades typically hit a stop that holds them in an extended position as the arrow penetrates a target object. Note that the cutting surfaces 54 of the mechanical blades also have to cut through the outer portion of a target, or the hide of an animal, as they are deployed during initial entry into a target. When this type of mechanical broadhead hits a target, there is a considerable amount of inertial loss due to the blade resisting entry and being deployed backward. This sudden and substantial reduction in velocity may result in less penetration into a target, such as an animal, and therefore be less effective. Also, the mechanical blades, as shown in FIG. 2D, have no give or flex in the event that they hit an object 95, such as bone within a game animal. The mechanical blades may break and will dramatically loose velocity if a hard object is hit by the blades. In addition, a blade hitting a hard object can deflect the arrow trajectory.
Material selection is also an important aspect of broadheads. A broadhead blade should be sharp to enable deep penetration. The broadhead blade is preferably durable, resistant to damage, chipping, permanent bending, blunting, and able to maintain a sharp edge. A broadhead blade should also be corrosion resistant to be able to withstand various environments in the field without compromising the integrity of the blades. Currently, broadheads are manufactured using materials such as austenitic stainless steels, martensitic stainless steels, and aluminum. These current broadhead materials have some undesirable attributes. Aluminum broadheads blades have low hardness and, as a result, are unable to maintain a sharp edge. The sharp edges quickly become dull during use, such as when passing through an animal's hide. Martensitic stainless steels, although having a high hardness, are relatively brittle and subject to chipping and breaking. In addition, martensitic stainless steels are susceptible to corrosion and can rust, particularly after sharpening. Austenitic stainless steels also have relatively low hardness and are incapable of maintaining a sharp edge during repeated use